From 18c734d7f2ca4e86730808b8b4900363cb705ed3 Mon Sep 17 00:00:00 2001
From: Arthur Gautier <arthur.gautier@arista.com>
Date: Sat, 3 Jun 2023 19:43:20 -0700
Subject: [PATCH 1/3] nixosTest: adds support for lib.extend

When lib overrides were used, before this commit, they would not be made
available in the configuration evaluation of nixosTest's nodes.

Sample code:
``` nix
let
  pkgs = import ./. {
    overlays = [
      (new: old: {
        lib = old.lib.extend (self: super: {
          sorry_dave = builtins.trace "There are no pod bay doors" "sorry dave";
        });
      })
    ];
  };
in
pkgs.testers.nixosTest {
  name = "demo lib overlay";

  nodes = {
    machine = { lib, ... }: {
      environment.etc."got-lib-overlay".text = lib.sorry_dave;
    };
  };

  testScript = { nodes }:
    ''
      start_all()
      machine.succeed('grep dave /etc/got-lib-overlay')
    '';
}
```
---
 nixos/lib/testing/nodes.nix | 1 +
 1 file changed, 1 insertion(+)

diff --git a/nixos/lib/testing/nodes.nix b/nixos/lib/testing/nodes.nix
index 6e439fd814db..f58759b4cdba 100644
--- a/nixos/lib/testing/nodes.nix
+++ b/nixos/lib/testing/nodes.nix
@@ -16,6 +16,7 @@ let
 
   baseOS =
     import ../eval-config.nix {
+      inherit lib;
       system = null; # use modularly defined system
       inherit (config.node) specialArgs;
       modules = [ config.defaults ];

From 562f879cd173525076b79fc9b04de77004ad37c8 Mon Sep 17 00:00:00 2001
From: Arthur Gautier <arthur.gautier@arista.com>
Date: Wed, 14 Jun 2023 23:12:44 -0700
Subject: [PATCH 2/3] runNixOSTest: adds support for lib.extend

When lib overrides were used, before this commit, they would not be made
available in the configuration evaluation of nixosTest's nodes.

Sample code:
``` nix
let
  pkgs = import ./. {
    overlays = [
      (new: old: {
        lib = old.lib.extend (self: super: {
          sorry_dave = builtins.trace "There are no pod bay doors" "sorry dave";
        });
      })
    ];
  };
in
pkgs.testers.runNixOSTest {
  name = "demo lib overlay";

  nodes = {
    machine = { lib, ... }: {
      environment.etc."got-lib-overlay".text = lib.sorry_dave;
    };
  };

  testScript = { nodes }:
    ''
      start_all()
      machine.succeed('grep dave /etc/got-lib-overlay')
    '';
}
```
---
 pkgs/build-support/testers/default.nix | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/pkgs/build-support/testers/default.nix b/pkgs/build-support/testers/default.nix
index 190ce72d0e63..d380dc6f30e1 100644
--- a/pkgs/build-support/testers/default.nix
+++ b/pkgs/build-support/testers/default.nix
@@ -97,7 +97,9 @@
   # See doc/builders/testers.chapter.md or
   # https://nixos.org/manual/nixpkgs/unstable/#tester-runNixOSTest
   runNixOSTest =
-    let nixos = import ../../../nixos/lib {};
+    let nixos = import ../../../nixos/lib {
+      inherit lib;
+    };
     in testModule:
         nixos.runTest {
           _file = "pkgs.runNixOSTest implementation";

From 933851135002dcc5564ac51263b5e24a5bb14ecc Mon Sep 17 00:00:00 2001
From: Arthur Gautier <arthur.gautier@arista.com>
Date: Sat, 3 Jun 2023 20:10:20 -0700
Subject: [PATCH 3/3] nixosTest: provide a test for lib.extend in nixosTests &
 runNixOSTest

---
 nixos/tests/all-tests.nix                    |  1 +
 nixos/tests/nixos-test-driver/lib-extend.nix | 31 ++++++++++++++++++++
 2 files changed, 32 insertions(+)
 create mode 100644 nixos/tests/nixos-test-driver/lib-extend.nix

diff --git a/nixos/tests/all-tests.nix b/nixos/tests/all-tests.nix
index 1b90b3e13807..02bef2039075 100644
--- a/nixos/tests/all-tests.nix
+++ b/nixos/tests/all-tests.nix
@@ -87,6 +87,7 @@ in {
   # Testing the test driver
   nixos-test-driver = {
     extra-python-packages = handleTest ./nixos-test-driver/extra-python-packages.nix {};
+    lib-extend = handleTestOn [ "x86_64-linux" "aarch64-linux" ] ./nixos-test-driver/lib-extend.nix {};
     node-name = runTest ./nixos-test-driver/node-name.nix;
   };
 
diff --git a/nixos/tests/nixos-test-driver/lib-extend.nix b/nixos/tests/nixos-test-driver/lib-extend.nix
new file mode 100644
index 000000000000..4fb7cf494aed
--- /dev/null
+++ b/nixos/tests/nixos-test-driver/lib-extend.nix
@@ -0,0 +1,31 @@
+{ pkgs, ... }:
+
+let
+  patchedPkgs = pkgs.extend (new: old: {
+    lib = old.lib.extend (self: super: {
+      sorry_dave = "sorry dave";
+    });
+  });
+
+  testBody = {
+    name = "demo lib overlay";
+
+    nodes = {
+      machine = { lib, ... }: {
+        environment.etc."got-lib-overlay".text = lib.sorry_dave;
+      };
+    };
+
+    # We don't need to run an actual test. Instead we build the `machine` configuration
+    # and call it a day, because that already proves that `lib` is wired up correctly.
+    # See the attrset returned at the bottom of this file.
+    testScript = "";
+  };
+
+  inherit (patchedPkgs.testers) nixosTest runNixOSTest;
+  evaluationNixosTest = nixosTest testBody;
+  evaluationRunNixOSTest = runNixOSTest testBody;
+in {
+  nixosTest = evaluationNixosTest.driver.nodes.machine.system.build.toplevel;
+  runNixOSTest = evaluationRunNixOSTest.driver.nodes.machine.system.build.toplevel;
+}